How do you entice low-income families to save? One of the great innovations at Bank Rakyat Indonesia (BRI) was to give people a chance to win prizes if they held savings in the bank's SIMPEDES account. Getting lottery coupons proved far more popular than getting interest. The idea flew in the face of the traditional view that families are always risk averse. The SIMPEDES success helped show that families could be averse to the risk of big losses—but simultaneously risk-loving over small bets. BRI implemented the idea in 1984, and it's now morphed into a tenet of behavioral economics.

The Economist reports that this same insight—that lotteries appeal when the stakes are small—is now being applied to deal with bus congestion in Singapore (based on a successful program by Infosys in Bangalore).